Lead forming or checking fixture



March 23, l954 M. B. MENTLr-:Y ET AL 672.716

LEAD FORMING OR CHECKING FIXTURE Filed Jan. 21, 1952 l2 MAX B'. MENTLEYl |0 Y oHN J.s|sMA f, WMV W g 60@ ATTORNEYS Patented Mar. 23, 19542,672,716 LEAD FORMING 0R CHECKING FIXTURE Max B. Mentley and John J.

Sigman, Detroit,

Mich., assignors to National Broach & Machine Company, Detroit, MichiganMich., a corporation of Application January 21, 1952, Serial No. 267,396

7 Claims. 1

The present invention ing or checking fixture.

v The present invention is designed to produce uniform rotational motionof a member in response to or in accordance with uniform axial movementof the member and accordingly, the mechanism may be employed either togenerate lead on a member when employed in conjunction with a metalworking tool such for example as a grinding wheel, or the mechanism maybe associated with suitable checking instruments, in Which case it willbe useful to check the lead or helix angle of a helicoidal surface.

It is an object of the present invention to provide simplified mechanismbased upon sound geometric principles designed to generate a true lead.

It is a further object of the present invention to provide mechanism forgenerating true lead, useful in either a metal Working or checkingdevice which employs an element having an involute surface thereoncarried by the rotatable member and acting in conjunction with a sinebar.

More specically, it is an object of the present invention to providemechanism designed to produce uniform rotational motion in accordancewith axial movement of a member by producing relative motion between asine bar located relates to a lead formin a plane perpendicular to theaxis of the member and an actuating arm secured to the member having aninvolute surface in contact with the sine bar.

It is a feature of the present invention to provide mechanism comprisinga support, a tirst slide movable rectilinearly on the support, a membermounted on the first slide for rotation about a xed axis parallel to thedirection of motion ofthe first slide, a second slide mounted on thefirst slide for rectilinear motion thereon in a direction perpendicularto the axis of said member, sine bar mechanism for effecting uniformmovement of said second slide in accordance with uniform movement ofsaid rst slide, an element rigidly carried by said member having aninvolute surface thereon, the origin of which is spaced from the axis ofsaid member by a distance equal to half the diameter of the base circleof the involute, and a sine bar carried by said second silde having itssurface in contact with the involute surface of said element.

It is a further feature of the present invention to provide mechanism ofthe character described in which said element is in the form of aninvolute acorn of circular transverse crosssection and having sidesurfaces which are involute in any axial plane, and means for biasingthe involute element into contact with its associated sine bar, saidbiasing means beingre versible so thateither one side or thediametrically opposite side of said element may contact the sine bar toproduce clockwise or counterclockwise rotation of the member upontranslation of the lirst slide in the same direction.

It is a further feature oi the present invention to provide as a newarticle of manufacture for use in mechanism of the character described,an involute acorn which is of circular cross-section in planesperpendicular to its axis and which has side surfaces which are ofidentical involute in any axial plane.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, wherein:

Figure 1 is a fragmentary plan View of the mechanism including the leadforming or checking fixture.

Figure 2 is an end elevation of the mechanism illustrated in Figure 1,with parts in section.

Figure 3 is a diagrammatic view illustrating the geometrical principleinvolved.

Figure 4 is a fragmentary elevational view of a modified form ofinvolute element and sine i) bar.

Figure 5 is a section on the line 5 5, Figure 4.

Referring now to Figure 1, the mechanism. comprises a base H3 havingrectilinear Ways l2 in which a slide i4 is mounted for rectilinearmotion. The slide I4 carries head and tailstocks indicated generally ati6 which include rotary spindles Iii adapted to support a rotary member2d. As illustrated herein, the rotary member 2d carries f' a gear' 22.It will be appreciated that where the mechanism illustrated herein isused as a grinding xture, suitable index mechanism will be provided topermit indexing of the gear 22.

Mounted on the rotary member 2i) is an arm 2li which as hereinillustrated includes a sleeve 26 by means of vwhich the arm 2t may beclamped to the member 20.

Mounted on the slide id is a plate 23 having ways de formed thereinwhich extend perpendicular to the axis of the rotary member' 2i).ll/iounted in the ways da for rectilinear movement therein is a secondslide 352. The slide 32is provided vvith an adjustable sine bar 3dherein illusstrated as pivoted to the second slide about an axisindicated at (iii and having an adjusting turnbuckle device indicatedgenerally at d3. By operation of the turnbuckle device the angular ityof the sine bar 313 may be adjusted as required.

The arm 2d at its outer end is provided with an element di! whichincludes an involute side surface in slidable contact with the adjacentsurface of the sine bar 34. Preferably, the element 4S is in theform ofan acorn which is of circular cross-section in any plane perpendicularto its whereby the involute surfacecthereof: infcontact?v with the sinebar 34 may beyaried at will..k Thus, after a period of use theelementlwamay; befadi-L justed to bring new elements ofitslsuriace.intovcoaction with the sine bar.

The base Il) includes a supporting portion 42 which is stationary withrespect thereto: Mount-'- ed on the support portion 42 is a secondfsinebarf 44 which is mounted for angular adjustment about a pivot axisindicated at 46 and which includes suitable mechanism; hereinillustrated as a vturnbuclcle 4.8, for `effectingY angular adjust ment'of the sine bar44.' The slide "32 includesa` projection Eilprovidediwith a` roller EZadaptedto .e

engage the, sine bar 44:

Securedtoy the ,plate 2B is abracklet 54'wliichin-- cludes anupwardlyjextending'portion-'56" carrying atransversely extending strapg.Intermediate slide 32 'are a plurality of tension'springs whicl'i' biasthe upper Slide 32 to therig'ht to"maintain the roller 52,' in contactwith vthesine 'bar 44:

Securedto the rotary member' Ziiis lan arm v62 the outer end"`offwhichis connected'to'a tension spring V(i4 which may beconnected tda'posti'ora post 68,to;apply'atcounterclockwise biasing vforce to the *member201 Thus, when the springb connects the arm 22 to the`post VliGiitbiases the rotaryjmemberin acounterclock.- wise direction" and'bringsvthebrinvo'lute acorn; 40 into Contact with .the sine'bardinitheYposition illustrated iniullj lines injFigure--2 If'thespring wereconnected to thepost; the rotary member ilwould be rotatedy clockwiseuntil' the Ainvolute acorn 4!! contacted. the sine bar 34 in. the posi=tion illustrated'in' dotted lines in Figure 2ty Referringnow toFigure 3,there is diagrame matically shown .the relationship'VA between the sine.bar 34', the, involute acornli., andthe rotary member 2li'. Fromthisfigurait willbe `observed that the. 24 is of such.length` with respectto theinvolute acornthat theorigin-'of-fthe'in volute surfaceofthe'acorn, which' isgdesig'nated in.this figure asljis located 'atta'distance froml the axisof the rotary member 2"which^"is 'equal tof;lhalf the` diameter of "the base CircletV BC of which the sidesurfacejof'the involutefacorniis an. involute. parent that ifj uniformtraverse'is;imparted'ito the sine bar SIlinthe directioniofLthe arrow 10; uniform rotation is Aimparted to ,the memb'er'Zi It` will. further.,be apparent ,.that'. the amount of rotation ,will depend .upon theangular adjustment of the sineib'a'r 34.'A

Moreover, it will' likewise be apparent that ii uniform..translation is.irripartedl to' the lower slide' .ilinrthedirection ofthe ways' 2; thesine bar mechanism includingjthe sine barA 4-4 andthe roller 52 willimpart uniform translation tofthe' upper slide'32 in a direction'perpendicular to' the ,directionl of `movenient of they lower 'slide' I4.y lt will further .be apparent that therate of translation'imparted`to the upper slide v`3i.' will bedependent upon the angular adjustmentof the sine bar44;

From the foregoing f it willbef apparent 1 that when th'eflowerfslide.-I4 ismoved alonglrtheways ifi-fat Iunitornr:rate;the upper: slide V321ismoved;v

upmrathe augmenta oixzthe leine iban-r 4,41M andifat From 'the'foregoingit willbe ap-v member 20 resulting the same time uniformrotation is imparted to thelrotaryvmember 20 dependenttupon .theangularity of the sine, ban-34.] Moreovenit' will be apparent that thedirection of rotation of the from movement of the lower slide I4 in agiven direction will be dependent uponf;whethersthecinvolute acorn 40 isin the full line, or. the dotted line position shown in F'surez.;`

Themechanismrfso far described may be used in conjunctionawith a machinefor producing helicoidal surfaces. Thus, in Figure 2 there isindicateddndttedflnes-a grinding wheel 14, the surfaceiofvwhich asindicated at 16 may be trimmed to involute shape. It will be understoodthat whenthe mechanism is employed ina grindenthe grinding *wheel14"'inuse willb'e rotated 'about 'the axis of a supportingshaftf18"andfwillbe maintained inA space while the slideV |4j isreversed. Since "uniform-traverse ofthe'sli'de 14S, as previouslydescribed in detail, results .in uniform roitational' movement ofthemember 20 this vuniiorm rotational movementwill--be imparted to the gear22 and' accordingly, the' grinder maybe usedlt'o grindinvolutehelicoidal surfaces on the gear, Where the mechanism .isemployedlfor grinding gear teeth .indexing` m'echanismwill be providedintermediate the `rotaryA member 20"'an'd thel gear 22 to permitshifting vroi "the gear 22,."relative..to the'rotarymember, 20 to grindall of, the teeth successively:

The same mechanismmay beemp'l'oyed'to 'check the accuracy ofpreviouslyproduced ,helicoidal surfaces by mounting'anindicator,iof"conyentional type in. such positionthat the ball'zontactithereofl engages a helicoidal 'surface on vthe work piece.' Itthis helicoidal surface extendsat' \a,true lead, translation of theslidef l 2 "'andresultantuniform rotation ofthe gear'22 will of courselnot produce any movement of the indicator contact ball. Thus themechanism. is useful 'eith'er in pro'ducingor trueing` helicoidal:surfaces, `or.y in' checking the accuracy of previouslyjformedortruedhelicoidal surfaces.

A s'previousl'y` stated',l the use'r ofi'the involute acorn` 40;provides a; multiplicity off' portions oi?r thev involute acornwithgrespect to rotationrabout its axis, so that ifwear developsalongoneside of the v.acorn it4 maybe shiftedslightly.v to bring anewand' unworninvolute surface into, Contact with. the sine bar 34..

However, in, its broadest ,aspectl L the; invention. does not dependupon the j useo 'the acorn as illustrated. herein.v Thus,rinFigures-ligand 5f' tli'ere isillustrated an elementl carriedmyanv arm.BZIhjaVingone surface84 thereof formedfto involute shape..The-surfacell "is equivalent to one-side. .of fa .spur .involute toothAand includes straight line,elements parallel, to. the,. axis.aboutwhichthearmfZ isplvotedr. Inthisgurethere. isi1lustrated.'asine bar .fB6 Whichmay-ebe-aflat: ban, but y:which is. herein.i1lustrated as.armand-y bar. The-.bar 86 l may.Y be vmounted tion, rotationaladjustment Aabout itsaxis so asfto bring. newlsuizl faeesinto contactwtnthe.involutecelemente. and provision may bemadeforrelativelateraladjustment .toA .bring the .sine bar.. 86 .intdcontactwithdiierent. portions., offthezinvolutesurace. 84al l While forVsimplicity the mechanism ,has,.been illustrated. as, comprising a, lowenslide -I 4..slid... able on a stationary base.. l0. and' carryingr``r a,transverse-upper slide. 32I,itwill:be-l.appreciatedf thatJequivalent@results ,could` be.obtainedwhere@ the. Slide; ltwerestationary, amicv the,-l relatiyei. motonarequired'ff to .producefrotmrmovementioi'e-i the member 20 results from translation of a member inthe position of the support 42. In this latter case the indicatinginstrument or the grinding wheel, or the like, would be mounted on theslide occupying the position of the support 42. The resultant rotarymovement of the member 20 would be accomplished in precisely the samemanner as previously described in detail. Other variations and changesin arrangement of the mechanism may obviously be made. The importantconsideration is that the rotational movement of the rotary memberresults from transverse movement of a sine bar acting in conjunctionwith an involute surface so designed that the origin of the involute isspaced from the axis of the rotary member a distance equal to half thediameter of the base circle of the particular involute.

There is thus provided single mechanism including simple adjustmentswhich may be employed to produce the required motion to form or checkhelicoidal surfaces extending at any selected helix angle and on partshaving any selected diameter. The mechanism is extremely accurate. As iswell known, the accuracy which may be obtained from sine bars is of thehighest type. The involute acorn 4U or the involute element 80 mayreadily be produced to provide contacting involute surfaces which are ofextreme accuracy. The mechanism is further characterized by itsflexibility in that it is possible to reverse the mechanism simply bychanging the connection of the spring B4 to form or check helicoidalsurfaces of either right or left hand.

The drawings and the foregoing specification constitute a description ofthe improved lead forming or checking xture in such full, clear, conciseand exact terms as to enable any person skilled in the art to practicethe invention, the scope of which is indicated by the appended claims.

What we claim as our invention is:

l. Mechanism for generating a true lead which comprises a base, a rstslide movable rectilinearly on said base, a second slide movablerectilinearly on said irst slide at right angles to the direction ofmovement of said first slide, a rotary support on said :rst slide, cammeans in the form of a rst sine bar on said base, a cam follower on saidsecond slide engageable with said first sine bar to move said secondslide laterally with respect to said rst slide upon movement of saidlirst slide, a second sine bar on said second slide, an arm extendingfrom said rotary support, and an involute follower on said arm inengagement with said second sine bar, said involute follower being inthe form of an acorn of circular transverse cross-section having sidesurfaces which are involute in axial cross-section.

2. Mechanism for imparting uniform rotational movement to a member inresponse to uniform axial movement thereof comprising an element havingan involute surface thereon, rigid means for supporting said elementfrom said member spaced from its axis of rotation a distance equal tothe base radius of the involute, a sine bar in contact with the involutesurface of said element and movable in a direction perpendicular tomovement of said member, and means for eifecting uniform movement ofsaid sine bar in accordance with uniform movement of said member in thedirection of its axis, said element being in the form of an acorn ofcircular transverse cross-section having side surfaces which areinvolute in axial cross-section.

3. Mechanism as dened in claim 2 comprising means for supporting saidacorn on said rigid means for rotation about its axis.

4. In mechanism of the character described, an involute acorn forsliding action against a sine bar, said acorn comprising support meansmounting it for bodily angular movement about an axis at a predetermineddistance therefrom, said acorn being of circular transverse crosssectionand having sides which in axial crosssection are involutes of a basecircle equal to twice the amount of said predetermined distance.

5. Mechanism for imparting uniform rotational movement to a member inresponse to uniform relative axial movement between said member andanother part which comprises an arm operatively connected to said memberfor rotation therewith, an element at the outer end of said arm having aside surface thereon which is an involute of a base circle whosediameter is equal to twice the distance from the axis of said member tothe origin of the involute, a sine bar movable in a path perpendicularto the direction of relative movement between said member and part, saidsine bar being in contact with the involute surface of said element, andmeans for imparting uniform movement to said sine bar in response touniform relative movement between said member and said part, saidelement being in the form of an acorn of circular transversecross-section having side surfaces which are involute in axialcross-section.

6. Mechanism for imparting uniform rotational movement to a member inresponse to uniform relative axial movement between said member andanother part which comprises an arm operatively connected to said memberfor rotation therewith, an element at the outer end of said arm havingopposite side surfaces which are involutes of a base circle whosediameter is equal to twice the radial distance from the axis of saidmember to the origin of said involutes, a sine bar movable in a pathperpendicular to the direction of relative movement between said memberand part, said sine bar being in contact with one of the involutesurfaces of said element, and means for imparting uniform movement tosaid sine bar in response to uniform relative movement between saidmember and said part, said arm and element being rotatable through anarc of more than degrees to bring either of the said diametricallyopposed sides opposite surfaces of said element into contact with thesine bar to provide for rotation of said member in opposite directionsupon relative movement between said member and part in the samedirection.

7. Mechanism as defined in claim 6, and reversible spring meanseffective to bias one side or the other of said acorn into contact withthe sine bar.

MA'X B. MENTLEY. JOHN J. SIGMAN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 515,595 Linden Feb. 27, 1894 2,294,733 Brady Sept. 1, 19422,387,166 Miller 1 Oct. 16, 1945 2,456,407 Green Dec. 14, 1948 2,574,112Kopec Nov. 6, 1951

